Liquid fuel pumping apparatus for supplying fuel to internal combustion engines

ABSTRACT

A FUEL PUMPING APPARATUS INCLUDING A PUMPING CHAMBER HAVING AN OUTLET THROUGH WHICH FUEL FLOWS DURING AN INJECTION STROKE, A STEPPED SHUTTLE SLIDABLE WITHIN A COMPLEMENTARY SHAPED BORE, THE NARROWER END OF SAID BORE BEING IN COMMUNICATION WITH THE PUMPING CHAMBER, MEANS ACTING TO URGE THE STEPPED SHUTTLE TOWARDS THE NARROWER END OF THE BORE AND THROTTLE MEANS FOR CONTROLLING THE ESCAPE OF FLUID FROM THE PORTION OF THE BORE DEFINED BETWEEN THE WIDER PORTION OF THE SHUTTLE AND THE STEP IN THE BORE DURING MOVEMENT OF THE SHUTTLE TOWARDS THE NARROWER END OF THE BORE, WHEREBY THE QUANTITY OF FUEL FLOWING THROUGH THE OUTLET CAN BE CONTROLLED.

Jan; 26,1971

I. FENNE LIQUID FUEL PUMPING APPARATUS FOR SUPPLYING FUEL TO INTERNALCOMBUSTION ENGINES Filed March 4, 1959 M THROT TLE j INV NTOE ATT RNEYSUnited States Patent 01 Rice 3,558,241 LIQUID FUEL PUMPING APPARATUS FORSUPPLYING FUEL T INTERNAL COMBUS- TION ENGINES Ivor Fenne, Greenford,Middlesex, England, assignor to CAN. Limited, London, England, a Britishcompany Filed Mar. 4, 1969, Ser. No. 804,082 Claims priority,application Great Britain, Mar. 8, 1968, 11,378/ 68 Int. Cl. F04b 23/12US. Cl. 417206 7 Claims ABSTRACT OF THE DISCLOSURE A fuel pumpingapparatus including a pumping chamber 15 having an outlet through whichfuel flows during an injection stroke, a stepped shuttle slidable withina complementary shaped bore, the narrower end of said bore being incommunication with the pumping chamber,

3,558,241 Patented Jan. 26, 1971 ery of an annular cam ring 14 whichsurrounds the distributor member and which is mounted in the body part.

In communication with the transversely extending bore 12, is alongitudinal passage 15 which, at its end remote from the bore,terminates in a delivery passage 16 which breaks out onto the peripheryof the distributor member. Moreover, formed in the body part are aplurality of angularly spaced outlet ports 17 with which the deliverypassage registers in turn and during the time when the plungers arebeing moved inwardly by the action of the cam lobes. The outlet ports,in use, are connected to injection nozzle units respectively, which aremounted to direct fuel into the combustion spaces respectively of theengine. The plungers together with the cam lobes constitutes aninjection pump, having a pumping chamber and by the arrangementdescribed a single injection pump serves a plurality of enginecylinders.

At another point, the longitudinal passage is in communication with aplurality of inlet passages 18 which means acting to urge the steppedshuttle towards the nar- 20 break out onto the periphery of thedistributor member rower end of the bore and throttle means forcontrolling the escape of fluid from the portion of the bore definedbetween the wider portion of the shuttle and the step in the bore duringmovement of the shuttle towards the at equiangularly spaced points. Inthe case of an apparatus which is intended to supply fuel to a fourcylinder engine, four such inlet passages 18 are provided and also fouroutlet ports 17. For registration with the inlet passages narrower endof the bore, whereby the quantity of fuel there is provided, in the bodypart, an inlet port 19 and flowing through the outlet can be controlled.

This invention relates to liquid fuel pumping apparatus through whichfuel flows to the inlet passages in turn, during the time when thedelivery passage is out of register with the outlet ports.

Mounted on the distributor member is the rotary part for supplying fuelto an internal combustion engine and of a vane type feed pump 20, thestationary part of which of the kind comprising an injection pumpincluding a reciprocable pumping plunger, a pumping chamber and anoutlet from said pumping chamber and through which fuel flows during aninjection stroke.

is mounted within the body part. The feed pump is provided with an inlet21 which, in use, is connected to a source of liquid fuel and also anoutlet 22 which is connected to a transfer passage 23 formed in the bodypart.

The object of the invention is to provide such an ap- Moreover, theinlet and outlet of the feed pump are able within a complementarilyshaped bore, the narrower end of said bore being in constantcommunication with said pumping chamber, means for urging said shuttlein one direction to expel fuel from the narrower end of the bore, stopmeans for limiting the extent of movement of the shuttle in the otherdirection and throttle means for controlling the rate of escape of fluidfrom the portion of the wider part of the bore lying between the widerpart of the shuttle and the step in the bore, during movement of theshuttle in said one direction, the arrangement being such that theinitial quantity of fuel expelled from the pumping chamber, during aninjection stroke, urges the shuttle into contact with said stop means,whereafter the remaining quantity of fuel flows through the outlet andthe amount by which the shuttle moves in said one direction isdetermined by the setting of said throttle means thereby controlling thequantity of fuel flowing through said outlet during the next injectionstroke.

FIG. 1 is a fragmentary view partly in elevation and partly incross-section of the invention.

FIG. Z'is a fragmentary view of another embodiment for effectingmovement of the shuttle of FIG. 1.

One example of a. liquid fuel pumping apparatus in accordance with theinvention and as shown in diagrammatic form in the accompanyingdrawings. With reference to FIG. 1 of the drawings, there is provided abody part 10 in which is mounted a rotary cylindrical distributor member11, which is adapted to be driven in synchronism with an engine (notshown) with which the apparatus is associated. At one end of thedistributor member there is formed a transversely extending bore 12 inwhich is mounted a pair of pumping plungers 13 which are adapted to bemoved inwardly as the distributor member rotates, by the action of camlobes formed on the internal periphinterconnected by a relief valve 24which controls the outlet pressure of the feed pump. In the presentexample, the transfer passage is in constant communication with theinlet port.

Formed in the body part is a stepped bore 25 having slidable therein acomplementary shaped shuttle 26. The narrower end of the bore is inconstant communication with the longitudinal passage 15 formed in thedistributor member, and the wider end of the bore is in constantcommunication with the outlet 22 of the feed pump, so that the shuttleis urged in a direction to expel fuel from the narrower end of the bore.Furthermore, at the wider end of the bore, there is mounted a stop 27which limits the extent of movement of the shuttle in the oppositedirection.

The portion of the wider part of the bore 25 lying between the widerpart of the shuttle 26 and the step in the bore, is in communicationwith the transfer passage 23 by way of a spring loaded non-return valve28, which is disposed to allow fuel under pressure to flow into the boreand to prevent flow of fuel in the opposite direction. Furthermore,extending from said portion of the bore is a passage in which is mountedan adjustable throttle 29, the setting of which can be determined by anoperator.

In use, during an injection stroke, in which position the apparatus isshown when the pumping plungers 13 are moving inwardly, the initialquantity of fuel, which i is expelled from the pumping chamber, flowsinto the the stepped bore by way of the non-return valve 28 and attheend" of the'inje'ction stroke when the delivery passage 16 has movedout of register with an outlet port and one of the inlet passages 18 hasmoved into register with the inlet port 19, the outlet pressure of thefeed pump acting on the wider end of the shuttle, moves the shuttle in adirection to expel fuel from the narrower portion of the bore 25 intothe longitudinal passage and the pumping chamber of the apparatus. Theextent of this movement of the shuttle is determined by the setting ofthe adjustable throttle 29 and it will be appreciated that if thethrottle is closed, then no movement of the shuttle can take plate. Atthe end of the filling stroke the pumping chamber of the apparatus iscompletely filled with fuel and during the next injection stroke themaximum quantity of fuel will be supplied to the engine, since no fuelwill be displaced from the pumping chamber into the narrower end of thestepped bore. If the setting of the throttle 29 is such as to allowmovement of the shuttle, then the quantity of fuel which is delivered tothe engine during the next injection stroke will be correspondinglyreduced.

In the above described example the stepped bore and shuttle, areaccommodated within the body part 10 of the apparatus, however, they maybe positioned within the distributor member. In one modification andshown in FIG. 2, instead of utilizing the output pressure of the feedpump to effect movement of the shuttle during the filling stroke of theapparatus, a coiled compression spring 30 or other resilient means maybe located within the wider portion of the stepped bore. In a furthermodification it can be arranged that the throttle means 2 9 etfects onlya limited control over the quantity of fuel which is delivered by theapparatus. :In this case further throttling means located upstream ofthe inlet port would be provided to control the fuel flowing directlyfrom the outlet of the feed pump to the inlet port and the throttlemeans 29 would be used to control, for instance, the maximum fueldelivery curve of the apparatus.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A liquid fuel pumping apparatus for supplying fuel to an internalcombustion engine and of the kind comprising an injection pump includinga reciprocable pumping plunger, a pumping chamber and an outlet fromsaid pumping chamber and through which fuel flows during an injectionstroke, a stepped shuttle slidable within a complementarily shaped bore,the narrower end of said bore being in constant communication with saidpumping chamber, means for urging said shuttle in one direction to expelfuel from the narrower end of the bore, stop means for limiting theextent of movement of the shuttle in the other direction, meansconnecting the portion of the wider part of the bore lying between thewider part of the shuttle and the step in the bore with the inlet to thepumping chamber and throttle means for controlling the rate of escape offluid from the portion of the wider part of the bore lying between thewider part of the shuttle and the step in the bore, during movement ofthe shuttle in said one direction, the arrangement being such that aninitial quantity of fuel expelled from the pumping chamber, during aninjection stroke, urges the shuttle into contact with said stop means,whereafter the remaining quantity of fuel fiows through the outlet andthe amount of which the shuttle moves in said one direction isdetermined by the setting of said throttle means, said movement causingthe narrow end of the bore to absorb a certain amount of fuel, whichupon the shuttle being shifted in said one direction, causes the shuttleto expel an amount of fuel equal to that absorbed, into the pumpingchamber for supplying to the outlet during the next injection stroke.

2. An apparatus as claimed in claim 1 including a fuel feed pump havingan outlet and passage means through which fuel can flow from the outletof the feed pump to the pumping chamber during a filling stroke of theinjection pump.

3. An apparatus as claimed in claim 2 including further passage meansthrough which said portion of the bore is in communication with theoutlet of the feed pump and a non-return valve mounted in said furtherpassage means to prevent the escape of fuel from said portion of thebore during movement of the shuttle towards the narrower end of thebore.

4. An apparatus as claimed in claim 3 in which the means to urge theshuttle in said one direction in the pressure in the wider end of thebore, which is in communication with the outlet of the feed pump.

5. An apparatus as claimed in claim 3 in which the means to urge saidshuttle in one direction is a resilient means acting on the shuttle.

6. An apparatus as claimed in claim 4 including a further throttle meansfor controlling the fiow of fuel through said first mentioned passagemeans.

7. An apparatus as claimed in claim 5 including a further throttle meansfor controlling the flow of fuel through said first mentioned passagemeans.

References Cited UNITED STATES PATENTS 3,433,160 3/1969 Kemp 1032.13,485,175 12/1969 Kemp et a1 103-2.1

CARLTON R. CROYLE, Primary Examiner US. Cl. X.R. 418l5

